Ok first off anybody who knows me on here knows I usually ask a ton of questions about my projects bit this is about my dd.Its a 2 nd gen dodge ram with the 360 awhile back the hvac started acting funny replaced every vac line I could find still no fix,next found out my plenum is leaking so I orderd the parts to fix but I haven't yet&today I go to run some errands&when I push my brakes I hear a hissing like when the booster goes bad.Ive checked the booster&cylinder &there ok.Now Im wondering could my leaking plenum gasket be causing these problems?When I bought my mustang it did the same thing hissing when applying brakes but booster was ok...ended up being a rusted out reservoir.So input?Could it be the plenum?

But Ive tested the booster&its holding vacuum.Ive turned it off&pumped brakes till hard held&started &it went slowly to ground&Ive started turned ofd&removed valve&heard the woosh.Like I said on my mustang it did the exact same thing&I replaced the booster&ot still did it ended up being a keak somewhere else that was causing the hiss@brakes&when I fixed that leak it fixed the hissing@brakes.Thats why Im wondering if its the plenum leak since it causes a vacuum leak in the crank case.

Just because it hold vacuum, does not mean it won't leak when the brakes are applies. Put shortly, there is a valve system on the booster that allows atmospheric pressure into the rear chamber when the brakes are applied. This is the ``boosting`` effect. There is a vacuum and an atmospheric valve, and if you hear hissing when applying brakes, this valve assembly is shot.

Just because it hold vacuum, does not mean it won't leak when the brakes are applies. Put shortly, there is a valve system on the booster that allows atmospheric pressure into the rear chamber when the brakes are applied. This is the ``boosting`` effect. There is a vacuum and an atmospheric valve, and if you hear hissing when applying brakes, this valve assembly is shot.

I got ya...not sure if this makes a difference or not but maybe my choice of words wasnt too good...its not reallyva hiss like a sucking or a leak more like when u push down on a kids bicycle air pump like shhw shhw sorry if thats a crappy explanation.

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.

User Name:

Password

Please enter a password for your user account. Note that passwords are case-sensitive.

Password:

Confirm Password:

Email Address

Please enter a valid email address for yourself.

Email Address:

Insurance

Please select your insurance company (Optional)

Log-in

User Name

Remember Me?

Password

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.